1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, and a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.
2. Description of the Related Art
Recently, an electrophotographic photosensitive member (organic electrophotographic photosensitive member) having a photosensitive layer comprising a charge generating material and a hole transporting material (charge transporting material) which are organic compounds has been widely used in an electrophotographic apparatus such as a copier and a laser beam printer.
Among charge generating materials, a phthalocyanine pigment and an azo pigment are known as a charge generating material having a high sensitivity.
On the other hand, in an electrophotographic photosensitive member using a phthalocyanine pigment or an azo pigment, the amount of photo carriers (holes and electrons) generated is large and thus electrons as counters of holes transferred by a hole transporting material tend to remain in a photosensitive layer (charge generation layer). Therefore, the electrophotographic photosensitive member using a phthalocyanine pigment or an azo pigment has a problem in that a phenomenon called ghost tends to occur. Specifically, a positive ghost having a high density in only a region irradiated with light at the time of pre-rotation and a negative ghost having a low density in only a region irradiated with light at the time of pre-rotation are observed in an output image.
Japanese Patent Application Laid-Open No. 2002-091044 discloses a technique in which an undercoat layer provided between a conductive support and a photosensitive layer comprises an electron transporting organic compound and a polyamide resin, thereby reducing variations in exposure potential and residual potential by an environment.
Japanese Patent Application Laid-Open No. 2007-148293 discloses a technique in which a charge generation layer and an intermediate later provided between a support and the charge generation layer contain an electron transporting material, thereby suppressing a ghost.
Japanese Patent Application Laid-Open No. H08-095278 discloses a technique in which a photosensitive layer comprises a benzophenone derivative, thereby enhancing gas resistance and suppressing deterioration in sensitivity and reduction in chargeability.
Japanese Patent Application Laid-Open No. 558-017450 discloses a technique in which a layer comprising a benzophenone derivative is provided between a support and a photosensitive layer, thereby suppressing deterioration in sensitivity after repeated use.
Currently, it is desired to suppress a ghost under various environments. Although a ghost particularly tends to occur under a low temperature and low humidity environment among various environments, the above techniques are not sufficient in terms of the effect of suppressing a ghost under a low temperature and low humidity environment.
An object of the present invention is to provide an electrophotographic photosensitive member with which a ghost is suppressed even under a low temperature and low humidity environment, and a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.